1. Field of the Invention
The invention relates to a crawler running gear, particularly for a construction machine, having a central section and two crawler supports with in each case a crawler track, the crawler supports being positioned in a longitudinal direction on both longitudinal sides of the central section and are fixed to cross members, which are in each case displaceably mounted in a displacement direction by means of at least one guide on the said central section.
2. Description of the Related Art
Such crawler running gears are more particularly used on construction machines such as cranes and grabs and more especially on earthworking machines, such as e.g. excavators, bulldozers, etc. due to their good all-terrain characteristics. The central section of the crawler running gear or said running gear as a whole is also referred to as a bogie. The crawler supports with a crawler track can also be referred to as track frames.
For the adjustment of the gauge of the crawler running gear, it is known to displace at right angles to the longitudinal direction the two crawler supports on the longitudinal sides of a central section. The track frames are telescopically constructed. Thus, in operation it is possible to set a maximum gauge, which increases the stability of the construction machine. However, a reduction of the gauge is appropriate for the transportation of the construction machine to and from the building site. A description of such a crawler running gear is provided in U.S. Pat. No. 5,598,896.
The cross members linking the central section and the mandrel with the two crawler supports or track frames can have a rectangular or also a circular cross-section.
In order to compensate the twisting with respect to one another of the two track frames resulting from ground unevennesses, in the case of circular, tubular cross members it is necessary to have a comparatively complicated design of the junction point to the track frames.
Compared therewith rectangular cross members can admittedly be more simply designed, but in the extended state rectangular cross members tendentially have a fit clearance between the cross members and the guidance thereof in the central section and this increases with greater extension widths. This clearance has a disadvantageous effect on precisely installing an earth-working implement or a vibrating support device, e.g. a vibratory pile hammer. The setting of a precise working point is then difficult and the implement has to be moved in the case of kinematic and also weight-based shifts of subassemblies and the set attachment or starting point must be readjusted.
The object of the invention is to provide a crawler running gear of the aforementioned type ensuring a very rigid connection between the cross members and central section.
This object is achieved by the crawler running gear having a central section and two crawler supports with in each case a crawler track, the crawler supports being positioned in a longitudinal direction on both longitudinal sides of the central section and are fixed to cross members, which are in each case displaceably mounted in a displacement direction on said central section by means of at least one guide, wherein at least one clamping element is provided with which a cross member can be braced at right angles to the displacement direction with respect to its guide.
Preferred embodiments of the crawler running gear according to the invention are given in the dependent claims.
According to the invention, the crawler running gear of the aforementioned type is further developed in that at least one clamping element is provided enabling a cross member to be clamped at right angles to the displacement direction with respect to its guide.
A fundamental idea of the invention is, unlike in the case of the prior art crawler running gears, in which there is a fixing of the cross members only essentially in the displacement direction, to now provide through clamping elements a bracing at right angles to the displacement direction, thereby ensuring a more secure fixing.
An important advantage of the invention is that with constructionally simple means it is possible to obtain a secure, rigid connection between the cross members and central section, so that a readjustment of the machine, particularly when working with a vibrating device, such as e.g. a vibratory pile hammer, is much less frequently necessary than in known crawler running gears. The corresponding operations can consequently be carried out in a shorter time and therefore less expensively on the building site.
In a particularly preferred embodiment of the crawler running gear the clamping elements are constructed as hydraulically operable clamping cylinders. Advantages result through the high force action attainable through the hydraulic cylinders, accompanied at the same time by a compact construction.
The clamping cylinders can have clamping jaws, whose contours are adapted to the cross member shape in order to obtain a maximum bracing effect. In addition, in order to obtain a maximum friction between the cross members and the clamping jaws, a coating and/or profiling can be provided on the corresponding contacting areas of the cross members and/or clamping jaws.
A construction in which clamping cylinders are provided on opposite sides for at least one of the cross members is advantageous with a view to the stability of the structure. In principle, the clamping cylinders can be located in any direction. To compensate vibrating movements in the vertical direction, it is particularly advantageous to position the clamping cylinders on the top and bottom of the cross members. The facing clamping cylinders are preferably mutually displaced in the displacement direction so that tilting occurs, so as to additionally fix the cross members.
A particularly stable bracing can be obtained if there are in each case four clamping cylinders for each cross member.
A further stability rise can be obtained by providing clamping elements, particularly clamping cylinders on at least one of the cross members in the displacement direction and at different positions.
A guide strut of the cross member can essentially have any random shape, particularly also a circular shape. However, preferably the guide strut of the cross member is angular, particularly rectangular in cross-section. This firstly simplifies the assembly and disassembly of cross members and crawler supports and secondly the clamping jaws of the clamping cylinders can be given a simpler design.
In a preferred embodiment of the invention for the displacement of the cross members hydraulic cylinders are provided, which can fundamentally be directly articulated to the crawler supports. The particular hydraulic cylinder can also be on the one hand connected to the associated cross member in a direct manner and on the other to the central section. Normally each cross member has one or two hydraulic cylinders.
Each crawler support is preferably fixed to two cross members. However, in certain cases there may be only one or several cross members per crawler support.